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By Robert Smith

Deposits are global, said Barrick Gold's Smith. This means that the mineral industry, by necessity, is global. "Manufacturers have considerable freedom to decide exactly where they wish to produce whatever it is that they sell," he said. "What we sell, on the other hand, must be produced where nature chose to lay it down. The question is not so much, whether to go global, as when to do it and how to go about it." The timing of international expansion depends on external factors, often political, Smith said, and on internal ones that relate to the company's size and stage of development. "In deciding how to expand, a company is largely deciding how to adapt its existing business strategy to activity on the world stage," he said Barrick entered 1997 with 1.58 kt (51 million oz) of reserves, Smith said, annual production of 93.3 t (3 mil- lion oz) and cash flow of $463 million. Reserves in- creased 40% in 1996 and production will begin to rise again significantly in 1999. "We believe our fundamental strategy is responsible for our early development and subsequent success," he said. Barrick entered the gold-mining industry in 1983. Its corporate mandate was to create shareholder value, Smith said. From the beginning, the company took a different approach - businesslike, entrepreneurial, strategic and focused. "Many mining companies start out with a technical team and develop business and financial expertise thereafter," Smith said. "In 1983, Barrick had the business people, and then moved into mining." First, it acquired part interest in two small operations, one in Alaska and one in Ontario. Then, in 1984, it merged with Camflo Mines, which operated a low-cost underground operation in Quebec.

Jan 1, 1997

By Evan Brinkerhoff, Steve Chorley

The largest hard rock TBM ever to bore in the USA, an 11.6 m diameter Robbins Main Beam TBM, recently underwent a planned in-tunnel diameter change to a more compact 9.9 meters. The first-of-itskind conversion process for the Main Beam TBM was undertaken 2.8 km into the bore and was not done inside a shaft or pre-excavated portal. This paper will detail the unique dual-diameter machine designed for the Mill Creek Drainage Relief Tunnel in Dallas, Texas, USA, machine performance, and successful size conversion process that took place in early 2021—a process that utilized the four C’s of construction to enormous benefit: Communication, Cooperation, Collaboration and Coordination.

Dec 1, 2022

By J. Hindman, E. Moeller

Vermiculite is currently mined from shallow (less than 25 m or 80 ft) surface deposits throughout the world. The largest producers are Palabora Mining of Phalabowra, South Africa (ore stock is a phlogopitemica), Xinjiang Yuli Xinlong Vermiculite of Korla, China, and W.R. Grace of Enoree, SC (ore stock is a biotite mica). Smaller operations are in Australia, Brazil, Russia and Zimbabwe. They also produce vermiculite on a continuous basis but do not export any significant amounts of product to North America. Intermittent and poorly documented production on a minor scale is reported from Argentina, Egypt, India and Uganda. Worldwide vermiculite production in 2004 increased1.7 percent to 432.8 kt (477,000 st). North American production declined, while African and Chinese production continued to increase.

Jan 1, 2005

In the last four years, 2007~2010, 9 out of 24 metal/nonmetal underground mine fatalities were caused by ground fall across United States of America (Mine Safety & Health Administration, MSHA). To reduce or eliminate incidents/accidents caused by ground fall, this paper clarified how to design and select ground support based on different ground conditions, how to use mine ground support standards, what geotechnical engineers and underground operators should do to keep mine production free of ground failures.

Jan 1, 2012

By Y. Guan

The dissolution behavior of silver in ammoniacal solutions with cupric ammine as an oxidant has been investigated using a rotating disc electrode. The rates of dissolution of silver were determined by an electrochemical means as well as a direct measurement of silver ions reported in the bulk solution as a function of time. The variables investigated included stirring speed, temperature, concentration of lixiviants, and pH of the solutions. The rate of dissolution under the conditions studied' was found to be controlled by an electrochemical reaction at the liquid/ solid interface with an apparent activation energy of 48.07 kJ /mole. The rate was found to be a half order with respect to the, concentration of cupric tetra-ammine, Cu(NH3)l+.; The results were explained in terms of a mixed' potential theory.

Jan 1, 1994

By Jorgen Elbrond, Xiaoli Tang

In this paper we apply continuous-time option pricing theory (Dixit 8 Pindyck 1994) to show how to obtain an optimal investment rule for a mining project which requires sequential in- vestments. The application per se is to some extent very simple. The main purpose of the paper, however, is to draw the attention of mining people to how the option pricing theory may be used to capital investment decisions. This topic in economics is quite new but is attracting a lot of attention.

Jan 1, 1996

By A. K. Dikshit, H. R. Murty, S. K. Gupta

This paper deals with the development of environment performance indicators (EPIs) for the steel industry. Environmental performance has become one of the key measures of business success. Emergence of continuing pressure from customers, employees, government and NGOs for environmental performance evaluation (EPE) of industries has led to evolve a framework for the development of sector specific environmental performance indicators. EPIs can be used by steel industry for assessing the continual improvement in environmental perfromance, selecting various eco-friendly options, benchmarking, environmental reporting, technology assessment and dissemination, evaluating environmental impacts and building EPIs based environmental management systems. The objective of this paper is to develop EPIs for steel industry and provide framework for development of environmental performance indicators based environmental management system and its integration with the overall management system. An indepth discussion has been presented concerning identification of EPIs, eavaluation of significance of EPIs, their prioritization and its integration with Environmental Management Systems. A new methodology has been proposed for implementing EPIs based environmental management systems . The material presented is derived in part from PhD studies of Rajesh Kumar Singh.

Jan 1, 2005

By T. Faulkner, S. A. Richards

"Classic engineering economics provides the mining engineer with a fundamental approach to choosing between capital spending alternatives. This approach has been heavily used over the years and is an accepted technique for most investment decisions. There is a shortcoming that I have run into over the 15 year period when I worked in business planning roles. The classic time value of money approaches such as Net Present Value, Return on Investment, and Internal Rate of Return provide good estimates, but the input assumptions may fall short of describing the real material differences required by these analysis techniques. If the cost benefit analysis is defined solely on the improvement of the item being replaced or improved, the true profitability of the decision may be overestimated. Productivity improvement based capital projects can yield more accurate forecasts when conducted in concert with a “bottleneck analysis”. INTRODUCTION A review of the Theory of Constraints, (Goldratt, Cox, 1984) Lean, (Womack, 2003) (Rattner, 2006) and Six Sigma (Cryger, DeFeo 2015) lead us to recognize that these process improvement methodologies are oriented to the manufacturing process. These systems generally involve a factory that the material moves through on the way to becoming a final product. The mining challenge has many similarities to manufacturing once the ore has been won and made ready for processing. Before that point, however, the process is somewhat inverted while the ore is being won. Instead of the material moving through the factory, the factory is moving through the material. The Theory of Constraints (TOC) was used in an underground context by Baafi, Cai and Porter at 2015 APCOM, but even this groups’ analysis did not carry the concept from mining to shipping of the final product. There can be spatially distributed data that can affect the mining throughput constraints, some of which can be determined from exploration results. Identifying constraints can lead us to mapping productivity bottlenecks on future mining. Knowing this may improve decision making by eliminating one of Jim Fishbein’s three deadly sins of strategic planning: incomplete planning. When evaluating capital investment alternatives you should evaluate the impact of any proposed improvements on the entire operation. At the core of any mining system is the materials handling system. This can be typically expressed as the system that handles the raw material from the “face” through processing and then handling the finished product as well as the waste material. A “Bottleneck Analysis” is an investigation into the factors limiting a material handling system’s productivity (Goldratt, Cox, 1984). Mining material handling systems are usually composed of several linked components such as draglines, shovels, loaders, hydraulic excavators, continuous miners, longwalls, highwall miners, bucket wheel excavators, LHDs, feeders, conveyor belts, stockpiles, crushers, processing plants with various circuits, and waste handling systems. Each of the aforementioned components has a slightly different throughput capacity. When these are linked in series, the one with the lowest throughput capacity limits all of the others, creating the bottleneck for the system. Every material handling system has a bottleneck. In the mining environment, a subtle, but very significant phenomenon may also occur. The bottleneck may change as a result of a change in the raw feed qualities, face recession, overburden depth, digability, learning curve, and many others factors which may be derived from the drillhole data. These parameters often change as a function of the location in the reserve base, and may also vary with time."

Jan 1, 2016

By T. Y. Yan

O2, NaCl03, H202, NaOCI and Ce+4 have been examined as oxidants in an alkaline carbonate system for uranium in situ leaching. The South Texas and New Mexico ores contained up to 2.6 meq/g of reducing compounds that consume oxidants in the leaching operation. Leaching rates did not increase linearly with the oxidation potential of the oxidants. A mild oxidant can be used to maximize uranium oxidation selectivity and oxidant efficiency. 02 can oxidize most of the uranium mineral with an adequate rate and high oxidant efficiency.

Jan 1, 1993

By Ulf Georg Gwildis

Overexcavation and ground loss events during pressurized-face TBMadvance in soft ground can result in unplanned deformations above the tunnel and damage to existing infrastructure. Successfully managing the risk of this occurring is crucial for any project in an urban area to proceed. Common risk management approaches include a combination of establishing suitable ranges of TBM operational parameters and using geotechnical instrumentation for deformation monitoring. Another risk management tool is material flow reconciliation, which varies depending on the specified mining method and the equipment choices by the contractor. This paper compares recent and ongoing projects in the Pacific Northwest regarding overexcavation risk management.

Jun 13, 2023

By Robert Dunne

Over the last eighteen months, there has been a dramatic r decrease in the gold price fom US$450/oz to a low of US$275/oz. The prospect of low gold prices, around US$300/oz, appears to be a reality the gold mining industry will have to face over the next couple of years. Already some high cost operations have closed and at others, cost cutting measures and rationalisation have been or are being undertaken. This paper reviews the operating cost of some Australian mines and highlights the potential for cost cutting and demon­strates individual impacts on the dollar's reduction in the cost per ounce of gold.

Jan 1, 1998

By Tim O’Neil

ISO 9000 is a system of quality standards that originated in Europe in the 1980s and has since been widely adopted by manufacturing companies throughout the world. The ISO 9000 standards have received less attention in the minerals industry. But, in part as a result of customer pressure, a trend is beginning to emerge for minerals producers to seek ISO certification. This is especially true among producers of industrial minerals. In early October 1994, SME's Industrial Minerals Division held a conference "ISO 9000 - uniting industrial mineral producers and consumers into quality partnerships," in Nashville, TN to bring people from the industry together to talk about their experiences with ISO 9000. William J. Miles, of Bentonite Corp. Inc., and A. Frank Alsobrook, of Alsobrook and Co., were cochairmen of the meeting. In his introductory remarks, Miles noted, "ISO 9000 is more than a quality program. It is a quality philosophy. Appropriately imple-mented, it is a contract between the supplier and the customer. It leads to continuous quality improvement and reduced manufacturing costs."

Jan 1, 1995

By S. P. Singh

In order to simulate the operation of coal extraction machines, a portable workability instrument has been designed. Initially, the tests were performed with the instrument on modeling material, which were followed by in situ tests on coal in underground mines. The peak and mean cutting resistance and work done to cut a unit length of coal were determined for coal as well as modeling material. In addition, rebound strength and dynamic penetration tests were also performed in situ. On the basis of the cutting characteristics of coal, a "Workability Index" has been developed and its role in the judicious selection of coal cutting machines has been discussed. With reference to prior works and the strength characteristics of coal, it was found that the coal plow may not be suitable for the seams under investigation and the shearer seems to be the only choice. It has been observed that peak cutting resistance and the "Workability Index" in the case of coal as well as modeling material depend upon compressive strength. The peak cutting resistance exhibited certain dependence upon the Schmidt rebound hardness and dynamic penetration strength of coal in situ.

Jan 1, 1984

By Sebastian Avalos, Julian M. Ortiz, Willy Kracht

Semi-autogenous grinding mills play a critical role in the processing stage of many mining operations. They are also one of the most intensive energy consumers of the entire process. Current forecasting techniques of energy consumption base their inferences on feeding ore mineralogical features, SAG dimensions, and operational variables. Experts recognize their capabilities to provide adequate guidelines but also their lack of accuracy when real-time forecasting is desired. As an alternative, we propose the use of real-time operational variables (feed tonnage, bearing pressure, and spindle speed) to forecast the upcoming energy consumption via machine learning and deep learning techniques. Several predictive methods were studied: polynomial regression, k-nearest neighbor, support vector machine, multilayer perceptron, long short-term memory, and gated recurrent units. A step-by-step workflow on how to deal with real datasets, and how to find optimum models and final model selection is presented. In particular, recurrent neural networks achieved the best forecasting metrics in the energy consumption prediction task. The workflow has the potential of being extended to any other temporal and multivariate mineral processing datasets.

Jun 16, 2020

By Harry Parker

Resource and Reserve Audits Becoming Increasingly Common Types of Audits -Review of Methodology (‘Fatal Flaw’) -Due Diligence – (‘Sign Off’) -Endorsement – (‘QA-QC’) Suggested Standards in Red

Jan 1, 2003

By Syd S. Peng, C. Y. Chen

Introduction The Surface Mining Control and Reclamation Act was passed in 1977 to put an end to the uneven environmental standards and enforcement established by various coal mining states in the US. One year after passage, the Secretary of Interior was directed to promulgate permanent program regulations implementing Title V provisions of the Act. These regulations were to form the basis for state regulatory programs under the Act and to allow states to assume primary regulatory responsibility. To implement the underground mining provision of the Act, the Secretary is directed in section 516(a) of the Act to promulgate rules. But they must take into consideration the differences between surface and underground coal mining. The regulations developed by the Secretary in 1979, with respect to subsidence control, included: • a subsidence control plan as part of the permitting process; • substantive provisions establishing performance standards for subsidence control; and • provisions providing for the prohibition of mining under perennial streams, impoundments larger than 24.6 dam3 (20 acre ft), and certain public facilities and urban areas. Industry challenged the Secretary's regulations implementing the subsidence control provisions. The litigation was consolidated with all other challenges to the permanent program regulations. (Permanent Surface Mining Regulation Litigation, Civil Action No. 79-1144; D. D.C., May 16, 1980.) In two opinions dealing with the multitude of issues raised by both industry and environmental groups, the US District Court of the District of Columbia ruled against industry. It upheld the promulgated subsidence control provisions. The US Court of Appeals stayed the appeals pending the agency's review and revision of its regulations. The regulatory reform was conducted in accordance with the order from the Secretary of Interior and the President in 1981. As a result, the subsidence control regulation was revised, reproposed, and finalized in June 1983 (Federal Register). This regulation, along with others, was again challenged by environmental groups and industry. On Oct. 1, 1984, the court, after finding the Secretary's reading of the Act reasonable, upheld the 1983 subsidence regulation except for one section. On Feb. 21, 1985, in accordance with the court's ruling, the Office of Surface Mining (OSM) suspended a portion of 30 CFR 817.121 (c)(2) concerning the damage correction requirement for structures or facilities and reproposed it on July 8, 1985 (Federal Register). In conjunction with a request for public comments, OSM now also seeks comments on the omission from the 1983 rule of the requirement in the 1979 rule regarding a presubsidence survey and monitoring of damage to structures. Technical issues related to subsidence regulations The subsidence regulations of June 1, 1983, consist mainly of two parts: a subsidence control plan as part of the permitting process; and substantive provisions establishing performance standards. The latter also includes provisions for prohibiting mining under certain areas. Under subsidence control plan section 784.20, minimum require-

Jan 2, 1986

By S. G. Malghan

W.H. Moyer In reference to the section “Excess pyrite, ” the author discusses difficulties in separating chalcopyrite from pyrite. A technique does exist, and has been used commercially, for the flotation, separation, and recovery, if desired, of both chalcopyrite and pyrite. The method was described in Mining Engineering, March 1966, “An Improved Flotation Method for Cornwall Sulfides. ” While it was not used on a porphyry copper ore, it was used on a chalcopyrite - pyrite-containing ore and might well have application. Both sulfides, chalcopyrite and pyrite, were floated simultaneously using xanthate as a collector and MIBC frother to produce a cleaned sulfide product. This concentrate was then thickened and conditioned at high solids with aeration and lime to a pH above 12.0 for a period of 1.5 to 2 hr. A supplemental suppressant, such as cyanide, could be used if necessary to sharpen the subsequent separation; however, it was not required at Cornwall. The conditioned sulfides were floated with two stages of cleaning to produce a highgrade chalcopyrite froth product and a pyrite sink product barren in copper. The separation at Cornwall gave a 28.6q. Cu grade chalcopyrite product and a pyrite analyzing 0.0670 Cu. A desliming step on the raw ore initially used at Cornwall for a period of time was later discontinued. Advantages to be found in using a strong sulfide collector, such as a xanthate, is the rapid flotation it induces and, generally, an ability to float at a coarser grind. A following regrind circuit could be used to give maximum liberation and produce a clean sulfide concentration. The “differential” separation is concerned primarily with grade and with assuring a barren pyrite for maximum recovery.

Jan 11, 1986

By S. K. Singh, P. R. Sheorey

To meet increasing demand of coal, underground mining is largely being replaced by the exploitation at deeper horizons and with greater complexities. The exploitation-proposition may be below not-to-be-disturbed surface properties or below water-bodies, posing a constant threat of inundation. Also, the mounting pressures to limit the adverse impacts on the environment bring the extraction-undertaking to face more challenges. An understanding of subsidence-mechanism and a rational quantification of subsidence parameters is a requisite herein. This paper presents such pragmatic quantification, validated at mine-sites in India. In comparison, better productivity, conservation and safety is ensured in this approach.

Jan 1, 1999

By K. Kovári, G. Anagnostou

Slurry and EPB-shield tunnelling have been successfully applied worldwide in recent years. Under extremely unfavourable geological conditions, however, face instabilities may occur. The present paper aims at a better understanding of the mechanics of face failure. For the case of slurry shield, attention will be paid to the time-dependent effects associated with the infiltration of slurry into the ground ahead of the face. Related topics, such as the stand-up time and the effect of the excavation advance rate, will be discussed. In the case of an EPB-shield, a distinction will be drawn between fluid-pressure and effective pressure in the chamber. The effective pressure can be visualized as a “grain to grain” contact pressure between the muck and the ground at the face. The water pressure in the chamber reduces the hydraulic head gradient in the ground and, consequently, the seepage forces acting in front of the face. The face is thus stabilized both by the direct support of the pressurized muck and by the reduction of the seepage forces in the ground. The paper includes normalized diagrams which allow the assessment of tunnel face stability.

Jan 1, 1997

By Jiang Su, Michal Uhrin

"The use of composite linings, consisting of permanent sprayed primary and secondary linings with a sandwiched spray applied waterproofing membrane is expected to improve efficiency and reduce lining thickness, but it also brings complex primary-secondary lining interaction. This issue is further complicated by the uncertainty regarding the long-term behavior and parameters of the sprayed concrete–sprayed membrane interface.This paper aims to address this issue by presentation of a series of numerical analyses of a typical shallow SCL tunnel in soft ground with a range of design assumptions on the interface behavior: (1) compression only; (2) compression and tension; and (3) compression, tension, and shear.The results demonstrate that the assumed interface behavior has a significant impact on the primary-secondary lining interactions. A design approach of ignoring the tension and shear bond at the interface may not be conservative particularly for serviceability. This paper explains the rationale behind these conclusions and discusses the implications for design.INTRODUCTIONSprayed Concrete Tunnel Lining SystemsSprayed concrete linings (SCL) have been used in conventional tunneling for decades. However, details of SCL systems may differ to a large extent depending on ground conditions and specific tunneling methodologies.In hard rock conditions, for example, drill and blast excavation is typically supported by rock bolts and sprayed concrete (NGI 2014). Such tunnels are usually designed fully drained and the above-mentioned support elements considered permanent without the need for a further inner liner. Therefore, there is no structural interaction between separate lining shells to consider.In conventional tunneling in the European Alps, a double shell lining is typically utilized, consisting of an outer (primary) sprayed concrete lining and an inner (secondary) cast-in-place concrete lining, separated by a waterproofing system. The primary lining normally includes rock bolts and may include other support elements. The waterproofing system is usually based on a plastic membrane and a geotextile fleece. The tunnel may be designed fully or partially drained or fully undrained. Although there are two structural lining shells interacting, investigation of such interaction is generally irrelevant to designers because the primary lining is considered only temporary (fully sacrificial in the long term). An overview of reasons for this assumption is given, for example, by Lemke (2014). The secondary lining is designed to resist all foreseeable loads on the tunnel. The primary lining may, in reality, interact structurally with the secondary lining during the life span of the tunnel. However, since the secondary lining design must cover all possible (extreme) scenarios, investigation of such interaction does not bring any value to the design."

Jan 1, 2016